Feature request: notifications on edited @mentions

@TDWTF-NodeBB-Development
So, not sure if the underpinnings of the post baker & notification systems would even support this, or whether or not there's a social engineering reason why it shouldn't be done, but a minor pain point that comes up fairly frequently in the ImpMis slum area of the forum is that once a post is submitted, any changes to the @mentions in the post will not send notifications. Meaning you either have to add a second post to @mention someone, or hope they have the thread on watching.

My desired feature MVP state:

adding additional @mentions via an edit of a post will send notifications for those @mentions

unless the user was already notified for that post due to a watching status (the same as they don't get an @mention notification for a post they get notified about due to watching a thread)

I think removing a notification if it hasn't been read (or maybe just undelivered?) by the target and a @mention gets removed from a post via post deletion or edit would also be useful behavior.

Given that it's a pretty esoteric use case, I figured I'd ask here to see if any of our Node plumbers think it's viable instead of asking upstream. Willing to cross-post there if people think that would be a better idea.

@Yamikuronue I don't think the original text is saved in any way for later processing. Obviously it could be and it would exist in the DB prior to saving. I dunno...it's been a while since I've looked at it.

Does the forum revoke notifications (e.g. if you upvote then un-upvote a post)? If so then it seems the simplest solution (conceptually, maybe not technically) would be to re-generate notifications for each @mention and revoke the ones that are no longer in the post. Also if possible, don't re-generate notifications if they've already been read for that post.

@hungrier
If anything, it's the opposite for notifications (as highlighted by the brief life span of the "vote balance" thred), at least for the 1,5,10,25 setting that (@boomzilla? someone here, I'm pretty sure) added

If you get exactly one upvote, and that upvote gets rescinded and then a later upvote gets applied, you'll get a second notification the next time. Similarly for all of the other thresholds - if you drop back below it, the next time you hit it, you get a new and additional notification.